Windows need help for porting from Xbox game pass to Steam

[Shuglee]

Me and a Friend were playing stardew valley for free because it was in the Game pass where it was 1€ for a month, now we wanted to port over to Steam.
The problem lies that when she hosts and i try to join, it says that my character doesnt belong to me.
We tried a couple of things to try and fix that:

• Deleting the UserID of the character in the save. The result was that the save was no longer loadable, resulting in a crash
• Replacing the steam "Stardew Valley" folder with the Xbox "Stardew Valley" folder. Result was that nothing changed.
• some other small various things trying to get my new userid to replace the old one.

I've tried googling about finding out a persons userid without any real results showing up about the stardew valley userid.
Does anyone know another way to find out a userid of a steam user, or another way to get rid of this problem?
Thanks in advance!